Methods and vectors (both DNA and retroviral) are provided for the construction of a Library of mutated cells. The Library will preferably contain mutations in essentially all genes present in the gene of the cells. The nature of the Library and the vectors allow for methods of screening for mutations...http://www.google.de/patents/US6855545?utm_source=gb-gplus-sharePatent US6855545 - Indexed library of cells containing genomic modifications and methods of making and utilizing the same